With the explosion of global, computer communications spurred by the Internet, on-line organizations' need for protection against cyber-criminals and cyber-vandals has also been expanding. For example, data and network sabotage incidents continue to increase—by over 35% per year from 1997 to 1999. Financial fraud perpetrated on-line has increased 25% in the same period. Viruses, worms, Trojan horses and other malicious code continue to plague enterprise and home users, and many are global in scope, such as the infamous “love bug” worm of 2000. Warfare has even gone on-line, with cyber-terrorists in hot spots such as the Balkans and the Middle East making attacks on web sites and servers, and as the avowed tool of nation-states, notably the United States of America and the People's Republic of China. Mainstream press coverage of these events has heightened privacy and security concerns, hindering the widespread adoption of Internet commerce.
Accordingly, organizations need network security to protect organizations from malicious attacks over the Internet, whether by hackers or from viruses. In fact, the market for network security is expanding rapidly, reaching a projected value of $10 billion by the end of the year 2001. Unfortunately, most network security approaches are ad-hoc and implemented on an organization-by-organization basis. These approaches not only tend to be staff-intensive and expensive, but they also quickly become out-of-date, falling behind the malicious technology that is constantly being developed by hackers. As a result, there is an urgent need for a scalable, network security architecture that can take advantage of economies of scale and simplify the provisioning of network security services to organizations.